Aerosol inhalator

ABSTRACT

An aerosol inhalator of the invention has an inner tube ( 22 ) forming part of a suction path, a capillary tube ( 40 ) extending within the inner tube ( 22 ) and configured to discharge a solution therefrom in conjunction with a user&#39;s inhalation, and a heater ( 56 ) extending in a direction perpendicular to the axis of the inner tube ( 22 ) so as to traverse the inner tube ( 22 ) and configured to receive the solution discharged from the capillary tube ( 40 ), wherein the heater ( 56 ) atomizes the received solution by heating to generate, inside the inner tube ( 22 ), an aerosol to be inhaled by the user.

TECHNICAL FIELD

The present invention relates to an aerosol inhalator capable ofgenerating an aerosol as a user inhales, to supply the user with thegenerated aerosol.

BACKGROUND ART

This type of aerosol inhalator is disclosed, for example, in PatentDocuments 1 to 4 identified below.

The aerosol inhalator disclosed in Patent Document 1 includes a suctionpipe provided with a mouthpiece, a solution supply source incorporatedinto the suction pipe and storing a solution to be aerosolized, adispenser capable of supplying a fixed amount of the solution at a timefrom the solution supply source to a dispensing position within thesuction pipe, and an electric heater for heating and thereby atomizingthe solution supplied to the dispensing position, to generate an aerosolinside the suction pipe.

The aerosol inhalator disclosed in Patent Document 2 includes anelectric heater and a high-frequency generator, in order to aerosolize aliquid fed by a pump.

The aerosol inhalator disclosed in Patent Document 3 includes an ink jetunit for aerosolizing a liquid.

The aerosol inhalator disclosed in Patent Document 4 includes a liquidsupply path utilizing capillarity, and an electric heater arranged atthe outlet of the liquid supply path.

CITATION LIST Patent Literature

-   Patent Document 1: PCT International Publication No. WO 2008/105918    A1-   Patent Document 2: PCT International Application-Japanese    Translation No. JP 2006-524494 A-   Patent Document 3: PCT International Application-Japanese Domestic    Re-publication No. WO 97/48293-   Patent Document 4: Unexamined Japanese Patent Publication No. JP    H11(1999)-89551

SUMMARY OF INVENTION Technical Problem

The aerosol inhalator of Patent Document 1 requires that the usermanually operate the dispenser before inhaling through the mouthpiece,or that the dispenser automatically operate simultaneously with theuser's inhalation. The use of the dispenser directly leads to increasein the size of the aerosol inhalator, and also the need for manualoperation of the dispenser is a hindrance to the user's easy inhalationof the aerosol.

Automatic operation of the dispenser enables the user to inhale theaerosol with ease, but in this case, the dispenser not only requires acomplicated structure but consumes electrical energy for the automaticoperation. Consequently, a high-capacity power supply is indispensablefor the dispenser and the electric heater, resulting in further increasein the size of the aerosol inhalator.

In the case of the aerosol inhalators of Patent Documents 2 and 3, it isdifficult to reduce the sizes of the aerosol inhalators because of theircomplicated structures, like the aerosol inhalator of Patent Document 1.The aerosol inhalator of Patent Document 4, on the other hand, has asimple structure, compared with the aerosol inhalators of PatentDocuments 1 to 3. However, like the aerosol inhalators of PatentDocuments 1 to 3, the liquid is aerosolized not by causing the liquid tocollide directly with the electric heater, and thus reliableaerosolization is not guaranteed.

An object of the present invention is to provide a small-sized aerosolinhalator which enables a user to inhale an aerosol with ease and alsoguarantees reliable aerosolization of liquid.

Solution to Problem

The above object is achieved by an aerosol inhalator of the presentinvention, which comprises:

a suction path connecting an atmosphere-exposed opening and a mouthpieceto each other and permitting air to flow from the atmosphere-exposedopening toward the mouthpiece;

a solution supply device configured to supply a solution from which anaerosol is to be generated, the solution supply device including

a solution supply source storing the solution, and

a capillary tube connected to the solution supply source and having adischarge end located in the suction path and opening in a directiontoward the mouthpiece, the capillary tube guiding the solution from thesolution supply source to the discharge end and, when the flow of air isproduced within the suction path, allowing the solution to be dischargedfrom the discharge end; and

a heater device configured to receive the solution discharged from thedischarge end and atomize the received solution by heating, the heaterdevice including

a power supply, and

an electric heater arranged immediately downstream of the discharge endand facing the discharge end at a predetermined distance from thedischarge end while permitting the flow of air, the heater beingconfigured to generate heat when applied with a voltage from the powersupply.

With the above aerosol inhalator, when the user inhales through themouthpiece, the solution is discharged from the discharge end of thecapillary tube. The discharged solution is received on the outer surfaceof the heater and at the same time is atomized in its entirety by heatgenerated by the heater, so that an aerosol is generated inside thesuction path. The user can therefore inhale the aerosol through themouthpiece.

Specifically, the heater extends in a direction perpendicular to an axisof the suction path and traverses the suction path. Preferably, thecapillary tube extends coaxially with the suction path.

Advantageous Effects of Invention

In the aerosol inhalator of the present invention, the solution isdischarged from the discharge end of the capillary tube in conjunctionwith the user's inhalation, and the discharged solution is received onthe outer surface of the heater, so that a total amount of thedischarged solution can be atomized on the outer surface of the heater,generating an aerosol inside the suction path. Accordingly, the user caneasily and effectively inhale the aerosol.

Details and other advantages of the aerosol inhalator of the presentinvention will become apparent from the following description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic longitudinal sectional view of an aerosolinhalator according to one embodiment of the present invention.

FIG. 2 illustrates a specific example of a liquid tank appearing in FIG.1.

FIG. 3 is an enlarged sectional view of a heater appearing in FIG. 1.

FIG. 4 illustrates the heater in FIG. 1 along with a power feed circuit.

FIG. 5 schematically illustrates part of the aerosol inhalator in astate before an aerosol is generated.

FIG. 6 schematically illustrates part of the aerosol inhalator in astate in which an aerosol is being generated, as viewed in alongitudinal section of an inner tube taken along a longitudinal sectionof the heater.

FIG. 7 schematically illustrates part of the aerosol inhalator in astate in which an aerosol is being generated, as viewed in alongitudinal section of the inner tube taken along a cross section ofthe heater.

FIG. 8 illustrates a malfunction of the aerosol inhalator caused incases where the distance between a capillary tube and the heater is toolong.

FIG. 9 illustrates a malfunction of the aerosol inhalator caused incases where the distance between the capillary tube and the heater istoo short.

FIG. 10 schematically illustrates a heating test apparatus fordetermining an optimum heater.

FIG. 11 is a graph showing measurement results obtained by the heatingtest apparatus.

FIG. 12 illustrates a modification of a sheath element.

DESCRIPTION OF EMBODIMENTS

As illustrated in FIG. 1, an aerosol inhalator 10 according to oneembodiment includes a cylindrical outer tube 12 opening at both ends,and a mouthpiece 14 detachably connected to a proximal end of the outertube 12. The outer tube 12 and the mouthpiece 14 are each made ofheat-resistant synthetic resin. The outer tube 12 has a lid 16 locatedat its distal end, and the lid 16 is detachable from the outer tube 12.

The outer tube 12 contains a power supply unit 18 as a source ofelectricity, a liquid tank 20 as a solution supply source, and an innertube 22. The power supply unit 18, the liquid tank 20 and the inner tube22 are arranged sequentially in the mentioned order from the lid sidecoaxially with the outer tube 12. The inner tube 22 communicates withthe mouthpiece 14.

The power supply unit 18 and the liquid tank 20 are each replaceable,and with the lid 16 detached from the outer tube 12, the power supplyunit 18 and the liquid tank 20 are replaced with new ones.

The power supply unit 18 includes a cell holder 24 and a commerciallyavailable battery cell, for example, an AA size cell 26, held by thecell holder 24. The cell 26 has a nominal voltage of 1.5 V and isarranged coaxially with the outer tube 12.

The liquid tank 20 is illustrated in detail in FIG. 2.

The liquid tank 20 includes a cylindrical tank casing 28. The tankcasing 28 has a plurality of ribs formed on an outer peripheral surfacethereof. The ribs are spaced from each other in a circumferentialdirection of the tank casing 28 and extend in an axial direction of thetank casing 28 except an end portion of the casing 28 close to the powersupply unit 18.

The ribs serve to form a plurality of axial passages 27 (see FIG. 1)between the outer surface of the tank casing 28 and an inner surface ofthe outer tube 12, and also serve to secure an annular chamber 29 (seeFIG. 1) between the aforementioned end portion of the tank casing 28 andthe inner surface of the outer tube 12. The annular chamber 29 isconnected to the axial passages 27.

A tube coil 30 is contained in the tank casing 28. The tube coil 30extends in the axial direction of the outer tube 12 and has oppositeopen ends. An inlet conduit 32 extends from one end of the tube coil 30to the outer surface of the tank casing 28 and opens on the outersurface of the tank casing 28 to be connected to the annular chamber 29.A check valve 34 is arranged in the inlet conduit 32 and opens only inone direction toward the one end of the tube coil 30.

An outlet conduit 36 extends from the other end of the tube coil 30 andis connected to a capillary tube 40 through a joint 38. The capillarytube 40 projects from the tank casing 28 into the aforementioned innertube 22 and is located coaxially with the inner tube 22. The projectingend of the capillary tube 40 forms a discharge end 42, which opens in adirection toward the mouthpiece 14. Another check valve 44 is arrangedin the outlet conduit 36 and opens only in one direction toward thecapillary tube 40.

An internal flow channel (inlet conduit 32, tube coil 30 and outletconduit 36) of the liquid tank 22 and the capillary tube 40 are filledwith a solution to be aerosolized, and the solution reaches thedischarge end 42 of the capillary tube 40. The solution may contain, forexample, propylene glycol, glycerin or the like.

As is clear from FIG. 1, the inner tube 22 extends from the liquid tank20 toward the mouthpiece 14 and is connected to an absorbent sleeve 48.The absorbent sleeve 48 is located in alignment with the inner tube 22and has an inner diameter identical with that of the inner tube 22. Aportion of the outer tube 12 surrounding the inner tube 22 and theabsorbent sleeve 48 has a larger thickness than a portion of the outertube 12 surrounding the power supply unit 18 and the liquid tank 20.

Specifically, the inner tube 22 is made of stainless steel or ceramic,for example. On the other hand, the absorbent sleeve 48 is, for example,a paper tube or hollow tubular paper filter capable of absorbing thesolution. The absorbent sleeve 48 has a volume sufficient to retain arequired absorption amount of the solution.

As illustrated in FIG. 1, the outer tube 12 has a plurality ofatmospheric ports 50 formed therein. The atmospheric ports 50 adjoin theliquid tank 20, for example, and are spaced from each other in thecircumferential direction of the outer tube 12. Each of the atmosphericports 50 extends from the outer peripheral surface of the outer tube 12and penetrates through the inner tube 22. Thus, the atmospheric ports 50provide atmosphere-exposed openings 52 that open on the outer peripheralsurface of the outer tube 12, and are connected to the annular chamber29 through the axial passages 27.

Accordingly, the atmospheric ports 50 and the inner tube 22 form asuction path connecting the atmosphere-exposed openings 52 to themouthpiece 14. Also, the atmospheric ports 50 serve to keep the interiorof the annular chamber 29 at atmospheric pressure, and as a consequence,the solution in the liquid tank 20 remains in a state such that thesolution is always acted upon by the atmospheric pressure through theopen end of the inlet conduit 32.

When the user inhales the air in the inner tube 22 through themouthpiece 14, a negative pressure is created in the inner tube 22, sothat ambient air is introduced into the inner tube 22 through theatmospheric ports 50. Such introduction of the ambient air produces,within the suction path, a flow of air toward the mouthpiece 14.

The negative pressure created in the inner tube 22 causes the solutionto be discharged from the discharge end 42 of the capillary tube 40 intothe suction path, namely, into the inner tube 22, and the amount of thesolution discharged is determined by the intensity of the negativepressure. On the other hand, the capillary tube 40 is replenished withthe solution from the liquid tank 20 in an amount corresponding to thedischarge amount. Since the solution in the liquid tank 20 is alwaysapplied with the atmospheric pressure as stated above, the solution inthe internal flow channel of the liquid tank 20 moves toward thecapillary tube 40 accompanying the replenishment of the solution.

A cylindrical heater 56 is arranged in the inner tube 22. The heater 56is located immediately downstream of the discharge end 42 of thecapillary tube 40, as viewed in the direction of the flow of airproduced in the suction path.

Provided that as shown in FIG. 3, the inner diameters of the inner tube22 and capillary tube 40 are D_(IT) and D_(CT), respectively, the outerdiameter D_(O) of the heater 56 is smaller than the inner diameterD_(IT) of the inner tube 22 and at the same time is larger than theinner diameter D_(CT) or outer diameter of the capillary tube 40.

That is, the outer diameter D_(O) satisfies the following relationship:

D_(IT)>D_(O)>D_(CT)  (1)

The heater 56 penetrates through the inner tube 22 in a diametricaldirection of the tube 22 and has an axis intersecting perpendicularlywith the axis of the inner tube 22. The heater 56 is supported at bothends by the outer tube 12.

Considering that the capillary tube 40 is located coaxially with theinner tube 22 as stated above, the discharge end 42 of the capillarytube 40 is hidden by the heater 56 when the heater 56 is viewed from thedownstream end of the inner tube 22. In other words, the cross sectionof the discharge end 42 can be totally projected onto the outer surfaceof the heater 56.

Further, when the solution is discharged from the discharge end 42 inthe aforementioned manner, the discharged solution forms a liquiddroplet at the discharge end 42, and a maximum diameter of the liquiddroplet is determined by the inner diameter D_(CT) of the capillary tube40. Provided the maximum diameter of the liquid droplet is D_(MAX), agap Z between the discharge end 42 and the heater 56 fulfills thefollowing relationship:

D_(MAX)>Z>D_(CT)  (2)

Thus, when the solution is discharged from the discharge end 42, thedischarged solution is received on the outer surface of the heater 56without fail.

Table 1 below shows the relationship observed where the solution ispropylene glycol (PG; density: 1.036 g/mm²), among the discharge amountand volume of the solution discharged in the form of a liquid dropletand the diameter of the liquid droplet with respect to the innerdiameter D_(CT) of the capillary tube 40 and the flow rate of intake airflowing through the inner tube 22.

TABLE 1 Capillary tube Cross- sectional Discharge Discharge Diam- Solu-D_(CT) flow area Intake air amount volume eter tion (mm) (mm) flow rate(mg) (mm³) (mm) PG 0.36 0.1 35 ml/2 sec 2.58 2.49 0.84 55 ml/2 sec 32.90 0.88 0.5 0.2 35 ml/2 sec 5.5 5.31 1.08 55 ml/2 sec 11 10.62 1.36

The liquid tank 20 illustrated in FIG. 3 has a structure different fromthat of the liquid tank already explained above. Specifically, theliquid tank 20 in FIG. 3 has an internal flow channel 30 a extending ina zigzag, in place of the coil tube 30. This means that the coil tube 30is not indispensable to the liquid tank 20.

The structure of the heater 56 will now be described in detail.

The heater 56 includes, for example, a Nichrome wire 58 as a resistanceheating element, and a cylindrical sheath element 60 enclosing theNichrome wire 58. In this embodiment, as is clear from FIG. 3, theNichrome wire 58 axially penetrates through the sheath element 60 threetimes and has two ends projecting from the respective opposite ends ofthe sheath element 60.

As illustrated in FIG. 4, the Nichrome wire 58 is connected in serieswith the aforementioned cell 26 via a power feed circuit 63, and thepower feed circuit 63 has a switch 64. Although not illustrated in FIG.1, the power feed circuit 63 and the switch 64 are arranged on the innersurface of the outer tube 12, and the outer tube 12 is provided, on itsouter surface, with a push button (not shown) for operating the switch64.

The sheath element 60 is made of a ceramic such as alumina or siliconnitride, and constitutes the outer surface of the heater 56. Further, asis clear from FIG. 4, an annular groove 62, for example, is formed inpart of the outer surface of the sheath element 60, and a ring-shapedheat-resistant net 64, which serves as a wetting enhancement element, ispreferably fitted around the annular groove 62. The net 64 directlyfaces the discharge end 42 of the capillary tube 40, and theaforementioned gap Z is secured between the discharge end 42 and the net64.

The sheath element 60 not only protects the Nichrome wire 58 butthermally connects the Nichrome wire 58 and the net 64. Specifically,where the cell 26 is in a usable state and the Nichrome wire 58 isapplied with a voltage of 1 to 1.5 V, the sheath element 60 performs thefunction of quickly transferring heat generated by the Nichrome wire 58to the outer surface of the heater 56 and keeping the heatingtemperature of the outer surface of the heater 56 within a temperaturerange required to atomize the solution. That is, the Nichrome wire 58and the sheath element 60 constitute an internal structure whereby theheating temperature of the outer surface of the heater 56 is kept withinthe required temperature range, and to this end, the sheath element 60has a predetermined thickness and volume.

Referring now to FIGS. 5 to 9, the principle of operation of the aerosolinhalator according to the embodiment will be explained. In FIGS. 5 to9, the net 64 of the heater 56 is not illustrated.

FIG. 5 illustrates a state in which the aerosol inhalator is ready foruse with the switch 64 of the power feed circuit 63 turned on. Theheating temperature of the outer surface of the heater 56 is quicklyraised and kept within the required temperature range, and since therelationship indicated by the aforementioned expression (2) isfulfilled, the solution in the capillary tube 40 is not atomized by theradiant heat from the heater 56. That is, no aerosol is generated.

On the other hand, when the user inhales through the mouthpiece 14 ofthe aerosol inhalator in the state illustrated in FIG. 5, the solutionis discharged from the discharge end 42 of the capillary tube 40 asmentioned above. Since the relationships indicated by the expressions(1) and (2) hold between the capillary tube 40 and the heater 56, thedischarged solution L is reliably received on the outer surface of theheater 56, as shown in FIGS. 6 and 7. Where the net 64 is fitted aroundthe outer surface of the heater 56, the discharged solution is receivedby the net 64 and then spreads over the net 64.

At this time, since the heating temperature of the outer surface of theheater 56 is already kept within the required temperature range, thedischarged solution L is immediately atomized by being heated by theheater 56, generating an aerosol X inside the inner tube 22. The usercan therefore inhale the aerosol X through the mouthpiece 14.

Also, where the heater 56 is provided with the net 64, the net 64 servesto enhance the wettability of the heater 56 with respect to thedischarged solution L, so that the discharged solution L can be atomizedover a wider area, enabling prompt generation of the aerosol.

As soon as the user ceases breathing in, the discharge of the solutionfrom the discharge end 42 of the capillary tube 40 stops immediately. Asis clear from the above explanation, since the gap Z between thedischarge end 42 and the outer surface of the heater 56 is greater thanat least the inner diameter D_(CT) of the capillary tube 40, thesolution in the discharge end 42 is not atomized by the radiant heatfrom the heater 56 insofar as the heating temperature of the outersurface of the heater 56 is kept within the aforementioned temperaturerange.

Accordingly, the generation of the aerosol stops at the same time as thecessation of the user's inhalation, so that the solution in thecapillary tube 40 is not wasted.

As a result, the user can inhale the aerosol without fail each timehe/she breathes in, and the amount of the aerosol inhaled by the user isdetermined by the intensity and duration of the user's inhalation.

On the other hand, even though the heating temperature of the outersurface of the heater 56 is kept within the required temperature range,the discharged solution L fails to be received on the outer surface ofthe heater 56 and drops to the inner surface of the inner tube 22, asshown in FIG. 8, if the relationship indicated by the aforementionedexpression (2) is not fulfilled and the gap Z is greater than themaximum diameter D_(MAX) of the liquid droplet of the solution. In sucha case, the discharged solution L is not atomized, so that the usercannot inhale the aerosol.

Conversely, if the gap Z is smaller than the inner diameter D_(CT) ofthe capillary tube 40, the solution in the capillary tube 40 is possiblyatomized by the radiant heat from the heater 56, as shown in FIG. 9. Inthis case, the aerosol X is generated independently of the user'sinhalation, with the result that the solution in the liquid tank 20 iswasted.

Thus, in the case of the aerosol inhalator of this embodiment, thedischarged solution L fails to be atomized, that is, the aerosol failsto be generated, or waste of the solution is unavoidable unless therelationships indicated by the expressions (1) and (2) are fulfilled andalso the heating temperature of the outer surface of the heater 56 iskept within an appropriate temperature range.

Specifically, it is necessary that the relationships indicated by theexpressions (1) and (2) be fulfilled and also that, where the solutionis propylene glycol, the heating temperature of the outer surface of theheater 56 be kept within a temperature range of 180 to 280° C.

The aerosol inhalator of the embodiment does not include a controlcircuit for controlling the heat generated by the Nichrome wire 58.Thus, in order to keep the heating temperature of the outer surface ofthe heater 56 within the above temperature range, the thickness (volume)of the sheath element 60 needs to be properly set.

If the sheath element 60 has a larger thickness, it takes a longer timefor heat to transfer from the Nichrome wire 58 to the outer surface ofthe heater 56 via the sheath element 60, and since the area of theoutside surface of the sheath element 60 increases, the amount of heatradiated from the sheath element 60 also increases. Thus, it is thoughtthat the larger the thickness of the sheath element 60, the lower theheating temperature of the outer surface of the heater 56 becomes.

In order to confirm such lowering of the heating temperature of theouter surface of the heater 56, the inventors hereof prepared heaters 56_(A) to 56 _(G) which differed from one another only in the thickness ofthe sheath element 60. The sheath elements 60 of the heaters 56 _(A) to56 _(G) had thicknesses progressively increasing in order of 56 _(A) to56 _(G) each by a fixed increment.

FIG. 10 illustrates a heating test apparatus for a heater 56 _(X) (Xrepresents any one of A to G).

The heating test apparatus includes a power feed circuit 66 for applyinga voltage to the heater 56 _(X), and the power feed circuit 66 includesa direct-current power supply 68 capable of varying the applied voltage,a shunt resistor 70 (1 mΩ), and a voltmeter 72. The heater 56 _(X) isconnected in series with the shunt resistor 70.

Further, the heating test apparatus includes a temperature sensor 74,which is capable of measuring the temperature of the heater 56 _(X),that is, the temperature of the outer surface of the sheath element 60.Specifically, the temperature sensor 74 includes a type K thermocouple.

When the heater 56 _(X) is connected to the power feed circuit 66 asillustrated in FIG. 10, a voltage is applied from the direct-currentpower supply 68 to the Nichrome wire 58 of the heater 56 _(X), so thatthe Nichrome wire 58 generates heat. The heat generated by the Nichromewire 58 is transferred through the sheath element 60, thus increasingthe temperature of the sheath element 60, and on the other hand isreleased to the outside from the outer surface of the sheath element 60.

Consequently, the heating temperature of the outer surface of the sheathelement 60 is determined by a difference between the amount of heatgenerated by the Nichrome wire 58 and the amount of heat released fromthe sheath element 60, and the rate of temperature increase of the outersurface of the sheath element 60 is determined by the rate of heattransfer through the sheath element 60.

A heating test was conducted on the heater 56 _(X) in such a manner thatwith the applied voltage, applied to the Nichrome wire 58 from thedirect-current power supply 68, sequentially varied within a range of0.8 V to 1.6 V, the heating temperature of the outer surface of thesheath element 60 was measured by the temperature sensor 74 with respectto each of the applied voltages of the Nichrome wire 58. The measurementresults are shown in FIG. 11.

As is clear from FIG. 11, the outer surface of the sheath element 60 ofthe heater 56 _(X) is heated to a higher temperature as the voltageapplied to the Nichrome wire 58 increases.

Considering, however, ordinary use of the AA size cell 26 which isexpected to apply a voltage of 1.0 V to 1.5 V, the heater 56 _(F) aloneis capable of keeping the heating temperature of the outer surface ofthe sheath element 60 within the aforementioned temperature range (180to 280° C.)

This means that where the heater 56 _(F) is used as the heater 56 of theaerosol inhalator 10 of the embodiment, the heating temperature of theouter surface of the heater 56 can be kept within the requiredtemperature range without the need to use a control circuit forcontrolling the voltage applied to the Nichrome wire 58.

Since the aerosol inhalator 10 need not be provided with such a controlcircuit, the load on the cell 26 is reduced, whereby the aerosolinhalator 10 can be used for a long period of time. Further, the use ofthe cell 26 serves to make the aerosol inhalator 10 smaller in size andslenderer, improving handiness of the aerosol inhalator 10.

If, on the other hand, the user inhales in a situation where the heatingtemperature of the outer surface of the heater 56 is lower than theaforementioned temperature range due to voltage reduction of the cell26, the solution discharged from the capillary tube 40 may beinsufficiently atomized and part of the discharged solution may possiblyadhere to the inner surface of the inner tube 22.

Further, it is also conceivable that even though the heating temperatureof the outer surface of the heater 56 is kept within the aforementionedtemperature range, the generated aerosol condenses on the inner surfaceof the inner tube 22, with the result that the solution adheres to theinner surface of the inner tube 22.

In such cases, as the user inhales, the adherent solution may movetoward the mouthpiece 14 and possibly flow into the user's mouth.

However, since the absorbent sleeve 48, which is a paper tube or paperfilter, is arranged between the inner tube 22 and the mouthpiece 14, theadherent solution, if moved toward the mouthpiece 14, is reliablyabsorbed into the absorbent sleeve 48 and does not flow into the user'smouth.

The present invention is not limited to the aerosol inhalator 10 of theforegoing embodiment and may be modified in various ways.

As regards the heater 56, for example, the resistance heating element isnot limited to Nichrome wire, and the cross-sectional shape of theheater 56 is not limited to circle and may instead be ellipse, polygonor the like.

The sheath element 60 may be made of metal and, as shown in FIG. 12 byway of example, may have a rough outer surface 66 formed on at least aportion thereof where to receive the discharged solution, in place ofthe aforementioned net 64. The rough outer surface 66 is constituted,for example, by a large number of narrow annular grooves spaced fromeach other in the axial direction of the sheath element 60, and when thedischarged solution is received on the outer surface 66 of the sheathelement 60, the annular grooves serve to spread the discharged solution,like the net 64.

Further, where the sheath element 60 of the heater 56 and the inner tube22 are to be made of the same ceramic, the sheath element 60 and theinner tube 22 are preferably formed as a one-piece molded article, andin this case, the number of parts of the aerosol inhalator can bereduced.

REFERENCE SIGNS LIST

-   -   12: outer tube    -   14: mouthpiece    -   18: power supply unit    -   20: liquid tank    -   22: inner tube    -   26: cell    -   40: capillary tube    -   42: discharge end    -   48: absorbent sleeve (paper tube, paper filter)    -   50: atmospheric port    -   52: atmosphere-exposed opening    -   56: heater    -   58: Nichrome wire (resistance heating element)    -   60: sheath element    -   64: net (wetting enhancement element)

1. An aerosol inhalator comprising: a suction path connecting anatmosphere-exposed opening and a mouthpiece to each other and permittingair to flow from the atmosphere-exposed opening toward the mouthpiece; asolution supply device configured to supply a solution from which anaerosol is to be generated, said solution supply device including asolution supply source storing the solution, and a capillary tubeconnected to the solution supply source and having a discharge endlocated in said suction path and opening in a direction toward themouthpiece, the capillary tube guiding the solution from the solutionsupply source to the discharge end and, when the flow of air is producedwithin said suction path, allowing the solution to be discharged fromthe discharge end; and a heater device configured to receive thesolution discharged from the discharge end and atomize the receivedsolution by heating, said heater device including a power supply, and anelectric heater arranged immediately downstream of the discharge end andfacing the discharge end at a predetermined distance from the dischargeend while permitting the flow of air, the heater being configured togenerate heat when applied with a voltage from the power supply.
 2. Theaerosol inhalator according to claim 1, wherein the heater extends in adirection perpendicular to an axis of said suction path and traversessaid suction path.
 3. The aerosol inhalator according to claim 1,wherein the capillary tube extends coaxially with said suction path. 4.The aerosol inhalator according to claim 1, wherein the distance isshorter than a maximum diameter of a liquid droplet of the solutionformed at the discharge end by surface tension of the solution.
 5. Theaerosol inhalator according to claim 4, wherein the distance is longerthan an inner diameter of the capillary tube.
 6. The aerosol inhalatoraccording to claim 4, wherein the capillary tube has a diameter smallerthan that of the heater.
 7. The aerosol inhalator according to claim 1,wherein the discharge end is arranged in a position such that thedischarge end is hidden by the heater when an interior of said suctionpath is viewed from the mouthpiece side.
 8. The aerosol inhalatoraccording to claim 1, wherein the heater has a non-smooth region on atleast part of an outer surface thereof and receives the dischargedsolution on the non-smooth region.
 9. The aerosol inhalator according toclaim 1, wherein the heater includes an internal structure which isconfigured to keep heating temperature of an outer surface of the heaterwithin a predetermined temperature range required to atomize thedischarged solution, by using only the applied voltage and heat radiatedfrom the outer surface of the heater.
 10. The aerosol inhalatoraccording to claim 1, wherein the heater includes a resistance heatingelement, and a sheath element enclosing the resistance heating element.11. The aerosol inhalator according to claim 10, wherein the heaterfurther includes a wetting enhancement element configured to cause thedischarged solution received on an outer surface of the heater to spreadover the outer surface.
 12. The aerosol inhalator according to claim 1,wherein the power supply includes a commercially available battery cell.